HDAC9 and hepatocellular carcinoma: Some HDAC inhibitors such as panobinostat (Choi et al., 2021), SAHA analogues (Srinivas et al., 2016), and traditional Chinese medicine galangin (Li et al., 2016) have been recently reported to regulate apoptosis in HCC through controlling the expression of pro- and anti-apoptotic genes (Buurman et al., 2016; Li and Seto, 2016).